Khan.scratchpad.disable(); Tiffany sells magazine subscriptions and earns $$10$ for every new subscriber she signs up. Tiffany also earns a $$20$ weekly bonus regardless of how many magazine subscriptions she sells. If Tiffany wants to earn at least $$67$ this week, what is the minimum number of subscriptions she needs to sell?
To solve this, let's set up an expression to show how much money Tiffany will make. Amount earned this week $=$ $ $ Subscriptions sold $\times$ Price per subscription $+$ Weekly bonus Since Tiffany wants to make at least $$67$ this week, we can turn this into an inequality. Amount earned this week $\geq $67$ Subscriptions sold $\times$ Price per subscription $+$ Weekly bonus $\geq $67$ We are solving for the number of subscriptions sold, so let subscriptions sold be represented by the variable $x$ We can now plug in: $x \cdot $10 + $20 \geq $67$ $ x \cdot $10 \geq $67 - $20 $ $ x \cdot $10 \geq $47 $ $x \geq \dfrac{47}{10} \approx 4.70$ Since Tiffany cannot sell parts of subscriptions, we round $4.70$ up to $5$ Tiffany must sell at least 5 subscriptions this week.